Self-destruct fuze

ABSTRACT

A self-destruct fuze comprises inner and outer rotors mounted in a housing for rotation relative to each other and the housing and having safe, armed and fired positions, a primary lead carried by the housing, a detonator carried by the outer rotor, inertia and spin-actuated detents for releasably locking the rotor together prior to spin decay, a detent ball holding the key in locking position prior to launch, a spin-actuated lever geared to the inner rotor and retarded by a timing mechanism for rotating the two rotors against a spring biased from an outer safe position, where it is initially held by the outer rotor, to an inner firing position in line with the detonator, to be struck thereby when the outer rotor is released from the spin key during spin decay and rotated by its spring to fired position.

United States Patent [1 1 Mellen 1 SELF-DESTRUCT FUZE [75] Inventor:George P. Mellen, Wayzata, Minn.

[73] Assignee: The United States of America as represented by theSecretary of the Army, Washington, DC,

[22] Filed: Oct. 30, 1973 [21] App1.No.: 41l,107

[52] US. Cl. 102/70 R, 102/71, 102/80 [51] Int. Cl. F42c 9/04 [58] Fieldof Search 102/70, 71, 80, 79, 78

[56] References Cited UNITED STATES PATENTS 2,943,573 7/1960 Graser102/78 X 3,465,676 9/1969 Simmen 102/80 3,724,384 4/1973 Donahue 102/793,786,759 1/1974 Mellen et al 102/80 X Primary Examiner-Samuel W. EngleAttorney, Agent, or Firm-Edward J. Kelly; Herbert Ber]; Thomas R. WebbNov. 19, 1974 [57] ABSTRACT A self-destruct fuze comprises inner andouter rotors mounted in a housing for rotation relative to each otherand the housing and having safe, armed and fired positions, a primarylead carried by the housing, a detonator carried by the outer rotor,inertia and spin-actuated detents for releasably locking the rotortogether prior to spin decay, a detent ball holding the key in lockingposition prior to launch, a spin-actuated lever geared to the innerrotor and retarded by a timing mechanism for rotating the two rotorsagainst a spring biased from an outer safe position, where it isinitially held by the outer rotor, to an inner firing position in linewith the detonator, to be struck thereby when the outer rotor isreleased from the spin key during spin decay and rotated by its springto fired posi- Hon.

9 Claims, 8 Drawing Figures PATENTE NOV 1 9 I974 SHEET 2 0F 2 IIIIIHIFIRED SELF-DESTRUCT FUZE BACKGROUND AND SUMMARY OF THE INVENTION Anexplosive projectile or shell is normally provided with a high explosivecharge and some form of fuze which is designed to detonate the explosivecharge when the shell impacts, or reaches the vicinity of the desiredtarget.

Problems arise when the shell fuze, for some reason, fails to functionin the target area, and the shell becomes a dud. Not only has the shellfailed to accomplish its intended mission, e.g. to destroy or damageequipment of the enemy and/or to inflict casualties on enemy personnel,but also the dud may be salvaged and re-used by the enemy.

Therefore, an object of the present invention is to prevent, or at leastminimize, the production of duds by providing the shell with aseIf-destruct fuze. This fuze could be the only fuze carried by theshell, but preferably, is a back-up fuze for the main fuze. The mainfuze may, for example, be a point detonating, or impact type, fuze. Onthe other hand, the self-destruct fuze of the present invention respondsto a different environmental element, namely spin decay.

The self-destruct fuze comprises a housing containing a primary lead,first and second arming rotors rotatably mounted in the housing relativeto each other and the housing and having safe, armed and firedpositions, means releasable during launch for locking one rotor in thehousing in safe position prior to launch, spinactuated means for lockingthe rotors against relative rotation prior to spin decay, spring meansnormally biasing the second rotor toward the safe and fired positions,spin-actuated means for rotating the first rotor, against the springmeans, from the safe position to the armed position after release of thereleasable locking means, a detonator carried by the second rotor, afiring member mounted in the housing in positionto be struck by thedetonator when the spring means rotates the second rotor from the armedposition to the fired position after release of the second rotor fromthe spinactuated locking means during spin decay, and an explosive leadconnected between the detonator and the primary lead when the detonatoris in fired position.

In the embodiment illustrated, both inertia and spinactuated releasablelocking means are provided. The spin-actuated locking means is acylindrical key having a slot forming a D-section engaging the tworotors and a spin arm held in locking position prior to launch by adetent ball and during spin by centrifugal force. The spin-actuatedrotating means is a spin-actuated lever having a gear meshing withanother gear on the first rotor. The gear rotation is retarded by a stargear and associated pallet. The firing member is a lever pivoted in thehousing and having a firing pin which is initially held in a safeposition by a portion of the second rotor, and spring-biased during thearming operation to a firing position in-line with the detonator.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a top plan view of a fuzeembodying the present invention in the safe condition, with the endplate removed.

FIG. 2 is an axial section view taken on line 22 of FIG. 1, with the endplate in place.

FIG. 3 is a similar view taken on line 3-3 of FIG. 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT FIGS. 1-8 illustrate, forexample, a fuze 1 embodying the present invention. Fuze 1 comprises acylindrical body 3 with an end plate 5 attached thereto and an axialprimary lead tube 7 containing a primary lead 9. The ends of tube 7 maybe open and aligned with an opening 10 in end plate 5, as shown, if thefuze l is to be inserted serially between a point-detonating fuze and abooster device.

Rotatably mounted on the upper end of the lead tube 7 is a first armingrotor 11 having an external gear 13 on the lower end. Rotatably mountedon rotor 11 is a shorter second arming rotor 15. Relative rotationbetween the two rotors 11 and 15 is prevented in the safe and armedcondition of FIGS. 1-4 and FIGS. 5 and 6, respectively, by a cylindricalspin key 16, having a notch 17 which leaves a D-shaped key section 18,rotatably mounted in substantially semi-cylindrical mating grooves 19 inthe rotors 11 and 15 (see FIGS. 2 and 4). The lower end of key 16extends into an arcuate recess 20 in body 3 and has an L-shaped arm 21having an end surface 21' which, in the safe condition, engages a ball22 at one end of a groove 23 of a semicircular cross section in body 3,to prevent inward movement of arm 20 (FIG. 4). Ball 22 is held withinrecess 23 by a quarter-circular groove 24 in rotor 15.

Rotor 15 is biased counter-clockwise (as seen in FIG. 1) in body 3 by acoil arming spring 25 seated in a chanml 26 in the rotor and abutting astop pin 27 mounted in a support piece 28 attached to body 3. Prior tolaunch of the projectile containing the fuze, rotor 15 is locked againstrotation by a spring-pressed axial detent 29 mounted in the rotor andextending into a hole 31 in end plate 5 (FIG. 3). At launch, the detent29 releases rotor 15 by inertia.

Prior to launch, and during launch prior to achievement of apredetermined spin velocity, the rotor 15 is also locked to body 3 bytwo spin detent levers 33 pivoted on piece 28 and spring-biased intolocking engagement with two notches 35 and 36 in rotor 15 (FIGS. 1 and2).

At a predetermined point during spin-up, the detent levers 33 swing outdue to centrifugal force and release the rotor 15. After such release,the rotor 15 is rotated clockwise, from the safe condition of FIGS. l-4to the armed condition of FIGS. 5 and 6, by a spin-actuated arming lever37 having a pivot stud 38 pivoted on body 3 and a drive gear 39 meshingwith gear 13 of rotor 15 (FIGS. 2 and 4). This rotation is retardedduring a predetermined time by a star wheel 41, having a small gear 42driven by gear 39, and a pallet 43 engaging the star teeth of wheel 41.

As shown in FIGS. 1, 5, 7 and 8, a combustible or explosive lead 45extends radially through the rotor 11 and tube 7, to the primary lead 9.An explosive detonator 47 is carried by rotor 15, in a positionout-of-line with lead 45 in the safe and armed conditions (FIGS. 1 andand in-line therewith in the fired condition (FIG. 7). A firing pinlever or hammer 49 has a pivot stud 51 extending through a clearanceslot 53 in rotor and into a pivot hole (not shown) in end plate 5. Lever49 comprises a conical firing pin 54 and an arcuate control arm 55 whichhas a side surface 56 that engages an outer shoulder 57 on the rotor 15in the safe condition of FIGS. 1-4 and initially holds the firing pin 54out-ofline with the detonator (FIGS. 1 and 2). In the armed and firedconditions, arm 55 fits within a shaped recess 58 in the upper edge ofrotor 11.

In operation, prior to launch, the parts of the fuze are held in theirsafe positions of FIGS. 1-4, as described above. At launch, the inertiadetent 29 and spin detent levers 33 release the rotor 15. Then, thearming lever 37, actuated by spin, rotates the two rotors 11 and 15,which are locked together by key 16, for approximately 60, to the armedposition of FIGS. 5 and 6, compressing spring 25, and retarded by starwheel 41 and pallet 43. During this rotation, the firing lever 49, whenreleased from surface 57 of rotor 11, is pivoted inwardly to firingposition by its spring, positioning arm 55 in recess 58. Also, ball 22,which initially blocked surface 21' of the arm 21 of spin key 16, movesby spin and centrifugal force along groove 23 and into a radial recess59 connected therewith, leaving the spin key held in position only byspin.

Upon spin decay, when the restoring force of the arming spring exceedsthe spin force on the spin key 16, the spin key 16 is rotatedcounter-clockwise by rotor 15, releasing the rotor 15 and permitting itto be driven counter-clockwise by spring 25, snapping the detonator 47against the firing pin 54. When the detonator 47 strikes the firing pin54, as shown in the fired condition of FIG. 7, the detonator is alignedwith the lead 45, thus the firing train to the primary lead 9 iscompleted by the final rotation of rotor 15.

What is claimed is:

1. A-self-destruct fuze for a spin-type projectile, comprising:

a housing including a hollow cylindrical body adapted to be mounted insaid projectile with its longitudinal axis coincident with the spin axisof the projectile, and a cover plate attached to the forward end of saidbody,

a'primary lead tube containing an explosive primary lead axially mountedin said body, at least the rear end of said tube being open for exposingsaid primary lead to an explosive charge in said projectile,

a firing arming rotor rotatably mounted on said tube,

a second arming rotor rotatably mounted on said first rotor, said rotorshaving safe, armed and fired positions,

means releasable during launch for locking one rotor against rotationrelative to said housing prior to launch,

spin-actuated means for locking said rotors against relative rotationprior to spin decay in said safe and armed positions,

springs means normally biasing said second rotor toward said safe andfired positions,

spin-actuated means for rotating said first rotor against said springmeans from said safe position to said armed position after release ofsaid releasable locking means,

an explosive detonator carried by said second rotor,

21 firing member mounted in said housing in position to be struck bysaid detonator when said spring means rotates said second rotor fromsaid armed position to said fired position after release of said secondrotor from said spin-actuated locking means during spin decay, and

an explosive lead in said first rotor aligned with said detonator andsaid primary lead when said detonator is in said fired position.

2. A self-destruct fuze as in claim 1, wherein said releasable lockingmeans comprises a spring-biased detent on said second rotor engaging ahole in said housing and released by inertia at launch.

3. A self-destruct fuze as in claim 1, wherein said releasable lockingmeans comprises two detent levers pivoted in said housing, spring-biasedinto engagement with detent notches in said second rotor, and releasedby centrifugal force during spin-up at launch.

4. A self-destruct fuze as in claim 1, wherein said spin-actuatedlocking means comprises a spin key including a D-shaped body sectionrotatably mounted in mating semi-cylindrical grooves in said rotors anda spin arm adapted to maintain said key in locking position during spinby centrifugal force.

5. A self-destruct fuze as in claim 4, wherein said spin key is held inits rotor locking position prior to launch by means of:

complemental arcuate grooves in said housing and said second rotor, and

a detent ball located in one end of said grooves and engaging said spinarm in said safe position of said second rotor.

6. A self-destruct fuze as in claim 1, wherein said spin-actuatedrotating means comprises:

a first gear on said first rotor, and

a spin-actuated arming lever pivoted in said housing and including asecond gear meshing with said first gear.-

7. A self-destruct fuze as in claim 6, wherein said spin-actuatedrotating means further comprises a delay means including a star wheelgeared to said second gear, and a pallet engaging the star teeth of saidstar wheel.

8. A self-destruct fuze as in claim 1, wherein said firing membercomprises a lever having one end pivoted in said housing and a firingpin at the other end movable between a safe outer position in which saidfiring pin is positioned out of the path of said detonator and an innerfiring position, and spring means biasing said firing pin toward saidfiring position.

9. A self-destruct fuze as in claim 8, wherein said lever comprises asurface that engages a shoulder on said second rotor to maintain saidfiring pin in said safe position prior to the rotation of said secondrotor to said armed position.

1. A self-destruct fuze for a spin-type projectile, comprising: ahousing including a hollow cylindrical body adapted to be mounted insaid projectile with its longitudinal axis coincident with the spin axisof the projectile, and a cover plate attached to the forward end of saidbody, a primary lead tube containing an explosive primary lead axiallymounted in said body, at least the rear end of said tube being open forexposing said primary lead to an explosive charge in said projectile, afiring arming rotor rotatably mounted on said tube, a second armingrotor rotatably mounted on said first rotor, said rotors having safe,armed and fired positions, means releasable during launch for lockingone rotor against rotation relative to said housing prior to launch,spin-actuated means for locking said rotors against relative rotationprior to spin decay in said safe and armed positions, springs meansnormally biasing said second rotor toward said safe and fired positions,spin-actuated means for rotating said first rotor against said springmeans from said safe position to said armed position after release ofsaid releasable locking means, an explosive detonator carried by saidsecond rotor, a firing member mounted in said housing in position to bestruck by said detonator when said spring means rotates said secondrotor from said armed position to said fired position after release ofsaid second rotor from said spin-actuated locking means during spindecay, and an explosive lead in said first rotor aligned with saiddetonator and said primary lead when said detonator is in said firedposition.
 2. A self-destruct fuze as in claim 1, wherein said releasablelocking means comprises a spring-biased detent on said second rotorengaging a hole in said housing and released by inertia at launch.
 3. Aself-destruct fuze as in claim 1, wherein said releasable locking meanscomprises two detent Levers pivoted in said housing, spring-biased intoengagement with detent notches in said second rotor, and released bycentrifugal force during spin-up at launch.
 4. A self-destruct fuze asin claim 1, wherein said spin-actuated locking means comprises a spinkey including a D-shaped body section rotatably mounted in matingsemi-cylindrical grooves in said rotors and a spin arm adapted tomaintain said key in locking position during spin by centrifugal force.5. A self-destruct fuze as in claim 4, wherein said spin key is held inits rotor locking position prior to launch by means of: complementalarcuate grooves in said housing and said second rotor, and a detent balllocated in one end of said grooves and engaging said spin arm in saidsafe position of said second rotor.
 6. A self-destruct fuze as in claim1, wherein said spin-actuated rotating means comprises: a first gear onsaid first rotor, and a spin-actuated arming lever pivoted in saidhousing and including a second gear meshing with said first gear.
 7. Aself-destruct fuze as in claim 6, wherein said spin-actuated rotatingmeans further comprises a delay means including a star wheel geared tosaid second gear, and a pallet engaging the star teeth of said starwheel.
 8. A self-destruct fuze as in claim 1, wherein said firing membercomprises a lever having one end pivoted in said housing and a firingpin at the other end movable between a safe outer position in which saidfiring pin is positioned out of the path of said detonator and an innerfiring position, and spring means biasing said firing pin toward saidfiring position.
 9. A self-destruct fuze as in claim 8, wherein saidlever comprises a surface that engages a shoulder on said second rotorto maintain said firing pin in said safe position prior to the rotationof said second rotor to said armed position.